Cut-off-valve gear



(No Model.)

No. 254.066. B;a,1; ted 1 21,1882.

n M w m a I UNITED STATES PATENT OFFICE.

MOTT rsrEvEns, OF LAKE CITY, MINNESOTA.

CUT-OFF-VALVE GEAR.

SPECIFICATION forming part of Letters Patent No. 254,066, dated February 21, 1882. Application filed December 23, 1881. (No model.)

To all whom it may concern:

Be it known that I, Mo'rtr T. STEVENS, of Lake City, in the county of Wabasha and State of Minnesota, have invented certain new and useful Improvements in Automatic Gut-Olf- Valve Gear for Steam-Engines; and I do hereby declare that the following is a. full, clear, and exact description thereof, reference being had to the accompanying drawing, and to the letters of reference marked thereon, making part of this specification, in which the figure is aside elevation, partly in section.

This invention relates to improvements on link-motions or automaticcut-off-valve gear for steam-engines, wherein a governor of any suitable kind will by the rise and fall of its balls adjust the link or block, and thereby actuate a cut-off valve at any desired point of the stroke.

In carrying out my invention it will be hereinafter shown that the link which actuates the valve-rod is vibrated by two independent eccentrics set on the fly-wheel shaft in such manner that the adjustment of the link or block will give the desired movement to the valves to out off at any point of stroke, as the position of the link may determine. It will also be shown that I employ a small steam or vacuum cylinder in combination with the link movement, and as a part of the same, for the purpose of causing such an adjustment of the link as will effect a cut-off at any desired point of stroke, which will control the speed of the engine automatically and in combination with the foregoing I employ a spring between the link and a piston which moves in a dash-pot, for the purpose of allowing the link to make a quick movement.

A designates the bed of a horizontal stationary engine; B, the steam-cylinder; B, the piston-rod; B the rod connecting the slide to the crank on the main shaft 0. These parts, together with the steam-chests and valves for admitting steam to the cylinder and cutting off, are constructed in the well-known manner.

D designates an eccentric, and l) the rod thereof, which receive motion from the main shaft 0 and actuatethe slide or main valve.

E E are the cut-off eccentrics on the main shaft, which are connected by rods a a to the vibrating link F. This link is adjustable in suitable guides by means of levers G G, which vibrate about a fulcrum at b. These two levers are rigidly fixed together, and the vertical lever G is suitably pivoted to the pistonrod of a small steam or vacuum cylinder, H. V

This cylinder and its valves, together with a governor, I, are mounted on a bracket secured to the engine-bed A.

On one arm oflever G is an adj nstable weight, W, for balancing the linker block F; and J is a rod connecting the lever G to this link or block.

K is a dash-pot, supported below lever G by the en gine-bed, in which dash-pot works vertically a piston, c, the rod d of which is connected to the extremity of lever G by the interposition of a spring, S.

The link or block F is connected to the valverod B of the cut-off valve, which rod is endwise movable in a suitable guide. (Not shown.) It is obvious that the cut-off valve would receive the same motion by pivoting the link F on a vibrated fulcrum and adjusting the block in the link.

The main eccentric gives motion to the main steam and exhaust valves.

The cutoff valve is connected to and driven by the link or block, which receives its vibration from one or more eccentrics set on the main shaft, so that the cut-otfrange of the link, measured by the strokes of the engine, is from the center to five-eighths stroke.

The link is raised or lowered by means of the connecting-rod and levers described, actuated by the piston in the small cylinder, the valve of which latter is operated by the governor. When the governor-balls drop steam is admitted into the piston end of the small cylinder and raises the link, so as to allow the steam to follow the piston as far as necessary to keep the engine up to a. given speed. When the governor-balls rise the parts at the back end of the small cylinder are opened, which allows the steam to-force the link down and cut off the steam sufficiently to keep the engine down to its regular speed.

The spring connecting the piston-rod of the dash-pot to lever G is designed to allow the link to make a quick movement, while the piston in the dash-pot moves very slowly.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. The combination of the auxiliary steamcylinder, the steam-valves "thereof actuated directly by the governor, the balanced levers G G, connected to the piston-rod of the said cylinder, the adjustable link connected to the lever G, and also to one or two eccentrics on the main shaft, and the dash-pot piston-rod connected to said lever G, substantially as described.

2. In an automatic link-motion of the char- MOTT T. STEVENS.

Witnesses:

ADELBERT WELLS, M. R. MERRELL. 

